This is Steven Salzberg's blog on genomics, pseudoscience, medical breakthroughs, higher education, and other topics, including skepticism about unscientific medical practices. Here's where I can say what I really think about abuses and distortions of science, wherever I see them.

Fish oil salesmen

Well, they’re not quite the modern-day equivalent of snake-oil salesmen, but the parallels are irresistible. In the 19th century, snake oil was promoted as a cure for joint pain and other ills, and the figure of the snake-oil salesman was widely ridiculed. (Ironically, snake oil is still used as a treatment in China today, despite the lack of any evidence for its efficacy.)

Today we have a new figure: the fish oil salesman. This modern figure, though, is no joke: he is a polished, sophisticated figure with the full weight of the FDA behind him. Should we buy his product?

Last week, while watching a major sports event, I was treated to a new commercial for a product called Lovaza, which I learned “helps to lower very high triglycerides in adult patients.” It’s a beautiful commercial, with an actor in a lab coat (am I supposed to think he’s a scientist?), carrying a clipboard and walking through a lab surrounded by blue aquariums. (Apparently the lab is under water.) You can see the ad here.

Lovaza, made by GlaxoSmithKline, contains a high dose of omega-3 fatty acids, the “good fat” contained in oily fish such as salmon and tuna. In 2004, the FDA announced that it would allow the following health claim for omega-3 fatty acids:

“Supportive but not conclusive research shows that consumption of omega-3 fatty acids may reduce the risk of coronary heart disease.”

Not surprisingly, this announcement gave a big boost to dietary supplements made from fish oil. Omega-3's are the fifth best-selling supplement in the U.S., with sales of $600 million per year, according to a 2008 Wall St. Journal article.

What’s new about Lovaza? Mainly this: no other fish oil supplement (and there are many) has FDA approval, as the TV ad made clear. What FDA approval means is that the manufacturing process for Lovaza has been rigorously evaluated and the product is guaranteed (well, almost) to contain what it is supposed to contain, without contaminants. (As I wrote just last week, many supplements contain harmful contaminants.) This approval transforms Lovaza (like magic!) from a supplement into a pharmaceutical, and you can only get it (in the U.S.) with a prescription.

Why bother to go through the FDA process when you can sell the same supplement over the counter? Here’s the clever part: as an FDA-approved treatment, Lovaza is eligible for insurance coverage, which also means that GSK can charge an exorbitant amount of money for it. As cardiologist and blogger Dr. William Davis explained on his blog, this means that people in his area are paying $3360 per year to take fish oil pills, which they could buy at the local Costco for $150/year. It looks like getting FDA approval was a great deal for GSK, although not such a great deal for the consumer.

Of course, the makers of fish oil supplements have responded with countless articles claiming that their products are just as pure as Lovaza, and they very well might be. I’m not going to examine that question here.

But all of this kerfluffle about FDA approval ignores the most basic question: does it improve your health to take high doses of omega-3 fatty acids?

Er, no. Or maybe.

A recent (2010) meta-analysis by scientists from McGill University looked at 29 randomized controlled trials involving over 35,000 patients. They found that

“Omega-3 fatty acids were not associated with a statistically significant decreased mortality or with restenosis prevention.”

(Restenosis is narrowing of the arteries). They did find a small reduction in both conditions, but it was not significant. It appears that the FDA’s 2004 conclusion may be overly optimistic. So: either no benefit or a small benefit, but in any case fish oil doesn’t cause harm.

Remember, the Lovaza fish oil salesman only claims that it helps to treat people with extremely high triglyceride levels (over 500, where normal is less than 150). He never said it would reduce your risk of heart disease – in fact, he says in the ad that Lovaza has not been shown to prevent heart attacks or strokes. What this all means to me is that, if you have really high triglycerides, then it won’t hurt to take a fish oil supplement, but I can’t see any reason to spend 20 times as much for Lovaza.

Or you could make sure to eat plenty of oily fish like salmon. Sushi, anyone?

8 comments:

I just want to clarify that that meta-analysis was in patients at high risk of cardiovascular events. So the results do not apply to all patients, only to those at high cardiovascular risk. Even though the reduction in total mortality was not significant, the Bayesian confidence interval pretty much ends at one, which means that there is a high probability that there is at least a small reduction in total mortality. I was puzzled as to why heart attacks and strokes were not endpoints, but I only read the abstract so that may be explained in the paper.

I agree with you that OTC fish oil pills or eating oily fish are probably just as good as the prescription product.

Although fish oil lowers triglycerides, I don't know whether lowering triglycerides with fish oil has been shown to reduce the risk of cardiovascular events. You would have to do a trial of people with high trigs who are also on a statin, since statins are standard of care for people at high cardiovascular risk, and see whether the fish oil added any benefit to the statin.

I agree with the sentiments of the article but feel I have to correct your definition of restenosis. This meta-analysis focuses on patients with high cardiovascular risk who have undergone interventional procedures. Restenosis refers to subsequent narrowing of a coronary artery which has previously been opened by balloon angioplasty or stenting.

And I'm really not surprised fish oils don't help much in this risk group.

nickloman - thanks for the clarification on restenosis. There are many studies of fish oil and I didn't want to try to summarize them all (or even a few). My main point is that Glaxo has cleverly created a "drug" from a supplement, allowing them to cash in, with the help of professionally-produced advertisements. Fish oil probably does have benefits if you eat it instead of less healthy oils (such as palm oil, for example), but no one needs to buy Lovaza to get those benefits.

Evolution only requires us to live long enough to breed and raise our children to self-sufficiency. We want to live longer than that (most of us, that is). So we are searching for ways, through diet, exercise, or other means - to live longer.

Anthony, nice can of worms you opened. One reason I think worth investigation would be the very large increase of processed foods in our diet, more fatty meats available at every turn. When we evolved we had to run to get some meat and did not sit around all day with a fast food store (restaurant or grocery fast food) every 100 ft. Also we ate much more vegetation and fiber than today. But a really significant reason: an especially huge imbalance of omega 3 to 6 ratio. This is an important consideration with Omega 3 bennies and we are getting too much 6, because it is infused into our foods through things like corn(rich in omega 6) being artificially added to almost every food in the grocery store (except the outside, healthier aisles). Great question.....don't stop investigating. I attend a class on this , so I learned a lot lately.